For industry control systems, temperature inputs are often acquired by thermocouples (TC) in resistance temperature detector (RTD) sensors. TC's connections to RTDs require cold junction compensation. Specifically, TCs/RTDs on a printed circuit board (PCB) use a cold junction for temperature compensation. The temperature detected by the sensor on the PCB is often regarded as the cold junction temperature.
However, abrupt environmental temperature disturbances (i.e. wind, exposure to heated wires or other PCB elements, exposure to the environment outside the control system cabinet, etc.), cause a difference between the on PCB sensor detected temperature and the temperature of the screw actually causing electric potential difference. This is a result of the varying thermodynamic properties of such elements (i.e. thermo capacity, thermo conductivity, etc.). This difference exists for a period of time even after the environmental temperature disturbance disappears. During this period, the control system temperature measurements may not be accurate and the control system performance may deteriorate as a result.
Currently, the solution to this problem is to physically add an environmental closure by wrapping the PCB temperature sensor and the screws of the TC/RTD cold junction, in order to insulate it from the external environment. This can effectively mitigate the temperature disturbance problem in some cases. However, it is also expensive and not fully robust to varying external and/or internal conditions. Accordingly, a need exists for methods and systems that mitigate environmental temperature disturbances in the TC/RTD cold junction used in control systems.